桥墩上环翼式防冲板定型试验研究
发布时间：2018-12-13 16:11
【摘要】：桥墩冲刷是桥梁水毁的主要原因之一。桥墩冲刷不但受许多因素影响,而且桥墩周围水流结构也很复杂。下降水流、桥墩两侧的马蹄形漩涡、桥墩尾部的尾流漩涡、桥墩两侧和桥墩墩后由床面附近释放的小漩涡,这几种漩涡体系组成了桥墩周围复杂的水流结构。虽然国内外很多专家对桥墩冲刷进行了大量试验和分析,但是对于桥墩冲刷的防护仍处于探索阶段,传统的桥墩防护方法都是被动的抵抗桥墩的冲刷,本文研究的是一种可以安装在桥墩上的新型防冲结构,其名字为“环翼式防冲板”,环翼式防冲板是主动降低下降水流对桥墩的冲刷,从而达到防护目的。 本试验是在三种流量、不同防冲板类型组合的工况下,量测最大冲坑深度及各测点三维瞬时流速。通过分析最大冲坑深度、桥墩周围三维时均流速及三维相对紊动强度,得出最佳防冲板类型及环翼式防冲板最大冲坑深度计算公式。主要研究成果包括： (1)对于2-2断面,随着水深不断变化,半幅比整幅防冲板的时均纵向流速变化范围大；’设置防冲板之后,时均横向流速在2测线0.3倍水深处有极值。设置防冲板明显减小了靠近河床底部的垂向流速。设置防冲板之后整体横向相对紊动强度大于无防冲板工况。 (2)对于5-5断面,设置防冲板前后纵向流速分布形状相似。整幅防冲板和半幅防冲板的纵向相对紊动强度减小程度相差不大。整幅防冲板所在位置以下测点的垂向相对紊动强度大于半幅防冲板。 (3)整幅防冲板与半幅防冲板对各断面2测线的三维时均流速影响效果几乎相同。 (4)环翼式防冲板为半幅时的防冲刷效果比整幅好,环翼式防冲板长轴和短轴越大,防冲刷效果越好,其中长轴a是主要影响因素。 (5)根据实测数据,得出半幅环翼式防冲板最大冲坑深度拟合公式
[Abstract]:The bridge pier scour is one of the main reasons of bridge water destruction. The scour of pier is not only affected by many factors, but also the structure of flow around pier is very complex. The downward flow, the horseshoe vortex on both sides of the pier, the wake vortex at the tail of the pier, and the small vortex released from the side of the pier and behind the pier from near the bed surface constitute the complex flow structure around the pier. Although many experts at home and abroad have carried out a lot of tests and analyses on the scour of the pier, the protection of the scour of the pier is still in the exploratory stage, and the traditional protection method of the pier is to resist the scour of the pier passively. In this paper, a new type of anti-scour structure which can be installed on the pier is studied, which is called "ring wing type anti-scour plate". The annular wing type anti-scour plate is active to reduce the erosion of bridge pier by descending current, thus achieving the purpose of protection. Under the conditions of three kinds of flow rate and different types of anti-scour plate, the maximum depth of scour pit and the 3D instantaneous velocity of each measuring point are measured. Based on the analysis of maximum scour depth, 3D mean velocity around pier and relative turbulent intensity, the formula for calculating the optimum type of anti-scour plate and the maximum crater depth of annular wing anti-scour plate is obtained. The main research results are as follows: (1) for 2-2 section, with the constant change of water depth, the time average longitudinal velocity of half amplitude is larger than that of the whole plate; After setting the anti-punching plate, the average transverse velocity has extreme value in the depth of 0.3 times water of the 2 measuring line. The vertical velocity near the bottom of the river bed is obviously reduced by setting the anti-scour plate. The relative turbulent intensity of the whole transverse is higher than that of the non-punching plate after the anti-punching plate is set. (2) for section 5-5, the shape of longitudinal velocity distribution is similar before and after the anti-punching plate is installed. The longitudinal relative turbulence intensity of the whole plate and the half plate is not different. The vertical relative turbulence intensity of the whole plate is higher than that of the half plate. (3) the effect of the whole plate and the half plate on the 3-D mean velocity of each section 2 line is almost the same. (4) the anti-scour effect of the annular wing plate is better than that of the whole plate, and the larger the long axis and the short axis, the better the scour prevention effect, in which the long axis a is the main influencing factor. (5) based on the measured data, a fitting formula for the maximum depth of the scour hole of the half-amplitude annular flange plate is obtained.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U442.32;U443.22
本文编号：2376823
[Abstract]:The bridge pier scour is one of the main reasons of bridge water destruction. The scour of pier is not only affected by many factors, but also the structure of flow around pier is very complex. The downward flow, the horseshoe vortex on both sides of the pier, the wake vortex at the tail of the pier, and the small vortex released from the side of the pier and behind the pier from near the bed surface constitute the complex flow structure around the pier. Although many experts at home and abroad have carried out a lot of tests and analyses on the scour of the pier, the protection of the scour of the pier is still in the exploratory stage, and the traditional protection method of the pier is to resist the scour of the pier passively. In this paper, a new type of anti-scour structure which can be installed on the pier is studied, which is called "ring wing type anti-scour plate". The annular wing type anti-scour plate is active to reduce the erosion of bridge pier by descending current, thus achieving the purpose of protection. Under the conditions of three kinds of flow rate and different types of anti-scour plate, the maximum depth of scour pit and the 3D instantaneous velocity of each measuring point are measured. Based on the analysis of maximum scour depth, 3D mean velocity around pier and relative turbulent intensity, the formula for calculating the optimum type of anti-scour plate and the maximum crater depth of annular wing anti-scour plate is obtained. The main research results are as follows: (1) for 2-2 section, with the constant change of water depth, the time average longitudinal velocity of half amplitude is larger than that of the whole plate; After setting the anti-punching plate, the average transverse velocity has extreme value in the depth of 0.3 times water of the 2 measuring line. The vertical velocity near the bottom of the river bed is obviously reduced by setting the anti-scour plate. The relative turbulent intensity of the whole transverse is higher than that of the non-punching plate after the anti-punching plate is set. (2) for section 5-5, the shape of longitudinal velocity distribution is similar before and after the anti-punching plate is installed. The longitudinal relative turbulence intensity of the whole plate and the half plate is not different. The vertical relative turbulence intensity of the whole plate is higher than that of the half plate. (3) the effect of the whole plate and the half plate on the 3-D mean velocity of each section 2 line is almost the same. (4) the anti-scour effect of the annular wing plate is better than that of the whole plate, and the larger the long axis and the short axis, the better the scour prevention effect, in which the long axis a is the main influencing factor. (5) based on the measured data, a fitting formula for the maximum depth of the scour hole of the half-amplitude annular flange plate is obtained.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U442.32;U443.22
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